Traditionally, much effort has been expended to improve the taste, color, odor or clarity of oral care compositions such as dentifrice (toothpaste), mouth rinse, and the like. Because of the nature of such compositions, the taste of a product may often be of more importance to consumers than the actual or perceived efficacy. Since many efficacious oral care components have undesirable taste, color, odor or clarity, efforts to improve these characteristics are common in the art. For taste, one way to remedy an undesirable product taste is to add additional components, such as flavors, that will improve the overall taste experience for the consumer. However, such remedies can be expensive and it may be difficult to entirely mask an undesirable taste. Improvement of color or clarity through dyes or other additives has similar issues.
Water-soluble surfactants such as alkyl phosphate surfactants are commercially available for use in a variety of consumer products, including oral care compositions. These anionic surface active organophosphate agents have a strong affinity for enamel surface and have sufficient surface binding propensity to desorb pellicle proteins and remain affixed to enamel surfaces. Such properties make these materials desirable for incorporation in oral care compositions such as toothpaste. However, these materials have not been widely commercialized in oral care compositions, despite their desirable properties. One reason for this lack of commercialization may be the negative taste and/or odor profile commonly associated with commercially available alkyl phosphate materials. Although taste may not be a consideration in other consumer product industries, such as laundry, shampoo or personal cleansing, it is an important consideration in oral care. Similarly, while any undesirable odor associated with materials used in laundry, shampoo or personal cleansing products can typically be remedied by the addition of perfume, perfume levels must be kept to a minimum in oral care compositions for consumer acceptance and could produce further unpleasant tastes when utilized.
Purification of surfactant materials through steam-stripping, vacuum-stripping, and/or carbon filtration processes is also generally known to beneficially remove impurities to increase efficacy, minimize undesirable side reactions, and the like. However, these purification processes have been found to be insufficient to remedy the unpleasant tastes and/or odors associated with commercially available water-soluble surfactant materials.
Liquid/liquid extractions (LLE) are generally known in the art as useful for separating components of a mixture, wherein the constituents have differing polarities which can be separated when mixed within two immiscible solvents that form a liquid bilayer after mixing. For example, LLEs are useful for purifying or cleaning samples which contain impurities of significantly differing polarity than the majority or desirable component(s) of the sample. This can be achieved by mixing a sample with a solvent that is immiscible with the primary liquid in which the sample is dissolved.
LLE has been utilized in chemical processing to reduce or eliminate undesirable by-products or contaminants. For instance, PCT Patent Application WO 2008005550 to Hoke, et al (Procter & Gamble) discloses a water washing procedure to remove polar sulfur impurities from peppermint oils to avoid malodor formation when formulated in dentifrice containing stannous ions. In U.S. Pat. No. 4,352,829 to Noyes, et al (Procter & Gamble) an ethyl acetate extraction of caffeine from coffee was shown to be an effective decaffeination process.
However, there is still an interest in finding ways to improve the overall taste and/or odor of water-soluble surfactants such as those used in an oral care composition that are efficacious, cost-effective, and desirable to consumers.